OpenAI has announced that ChatGPT free users will be upgraded to the default model, GPT-5.6 Luna. With these free users of ChatGPT will be offered unlimited text chats and increased access to its latest AI models. The company said the changes will begin rolling out this week, with unlimited texting and a new Think button for tougher questions coming next week.The update also includes improvements for paid subscribers. Plus and Pro users are getting an updated version of GPT-5.6 Sol in ChatGPT, along with a new slider that lets them choose how much reasoning the chatbot applies before generating a response.
GPT-5.6 Luna becomes the default model for Free users
According to OpenAI, GPT-5.6 Luna replaces GPT-5.5 Instant as the default model for ChatGPT Free and Go users. The company said the new model is designed to reduce factual mistakes, with internal evaluations of financial, medical, and legal prompts showing that responses containing at least one factual error were about 62% less common than with GPT-5.5 Instant.Starting next week, Free and Go users will also receive unlimited text chats. Limits will continue to apply to file uploads, image generation, voice interactions and other non-text features.OpenAI is also introducing a new Think button that allows Free users to request higher reasoning for more complex questions without switching models.
Changes for ChatGPT Plus and Pro users
For Plus and Pro subscribers, OpenAI has updated GPT-5.6 Sol in ChatGPT’s chat experience. The company said the revised model is intended to provide more focused answers with less unnecessary formatting and fewer mistakes involving dates, numbers, sources, rules, and assumptions.Users on these plans will also see a new reasoning slider across web, desktop and mobile versions of ChatGPT. The control allows users to adjust how much processing the model performs before responding, depending on whether they need a quick answer or a more detailed response for tasks such as research, writing, coding or planning.
OpenAI’s GPT-5.6 model family expands
Alongside the ChatGPT updates, OpenAI has made the GPT-5.6 model family generally available following a limited preview. The lineup includes GPT-5.6 Sol, GPT-5.6 Terra and GPT-5.6 Luna.According to the company, GPT-5.6 Sol introduces additional reasoning options, including max and ultra modes. Ultra coordinates multiple AI agents in parallel for complex workflows, while Programmatic Tool Calling in the Responses API allows developers to build workflows that process intermediate data more efficiently.OpenAI also said GPT-5.6 Sol, Terra and Luna recorded higher scores than several competing models across internal and third-party evaluations covering coding, long-running professional workflows and general reasoning, while using fewer tokens or lower estimated costs in several benchmarks.OpenAI said GPT-5.6 includes updated safeguards developed through human red teaming, automated testing and evaluations conducted with external organisations before launch. The company added that additional protections have been introduced for users under 18, including restrictions around age-sensitive content and stronger system-level safeguards.The updated GPT-5.6 Sol and reasoning slider are rolling out to Plus and Pro users today. This week, Free and Go users will see the rollout of GPT-5.6 Luna as the default model. Unlimited text chats and the Think button will be available next week (with abuse guardrails).
